The present invention relates to a glow discharge generating apparatus which is capable of generating a glow discharge between an anode and a cathode by applying a pulse voltage between the anode and the cathode and, more particularly, to a glow discharge generating apparatus having stabilizing means for stabilizing the glow discharge by suppressing a glow to arc transition.
A glow discharge is utilized, for example, in a gas laser oscillator or an ozone generator. In a glow discharge, electrons generated by the ionization of gas are locally concentrated when a discharge becomes thermally unstable in one region, or when a great deal of negative ions of carbon monoxide CO.sup.-, oxygen O or oxygen gas O.sub.2 are generated, or when a space charge distribution is caused to be uneven by the existence of projections on the surface of the anode, for example. It is understood that such a local concentration of electrons causes a glow discharge current to be locally concentrated at the cathode, resulting in a glow to arc transition. When this glow to arc transition occurs, the output of the gas laser oscillator, for example, decreases considerably, or the amount of generated ozone decreases in the ozone generator.
In order to prevent the above-described glow to arc transition, a predetermined gas has been passed between the anode and cathode at a high speed, or ballast resistors have been respectively inserted into needle cathode electrodes in a conventional gas laser oscillator. Since the gas laser oscillator of this gas flowing type, however, requires a circulator for circulating the gas, it was difficult to reduce the size of the laser oscillator, and it was impossible to increase the oscillation efficiency of the laser oscillator provided with the above ballast resistors, due to the loss of energy of the ballast resistors. In order to prevent a glow to arc transition in the conventional ozone generator, a silent discharge system has been adopted to suppress the concentration of a discharge current in a discharge space by inserting a dielectric member between the anode and cathode. Since this silent discharge system, however, has a limit in the dielectric strength of the member, a voltage value to be applied between the anode and cathode is limited. Therefore, the distance between the anode and cathode cannot be increased, and thus, the amount of ozone generated in the space between the anode and cathode cannot be increased.